Current indicator or detector.



PaLizmtec July 6, 1909.

D; BBU "IL CURRENT INDICATOR OR DETEGTR.

APPLIUATION FILED AUG,15, 1908.

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emrroen n. Hancock, or NEwYoRK, N. Y.

CURRENT INDICATQR OR DETECTOR.

Specification of Letters Patent.

Patented July e, e.

Applieatlon filed August 15, 1908. Serial No. 448,699.

To all whom it may concern.'

Be itV known that I, CLIFFORD I). BAB- COCK, a citizen of the UnitedStates, residing' at New York, in the county of New York and State ofNewYork, have invented certain new and uselul Improvements in (lurrentflndieators or DeLectora; and I do hereby de elare the following to he alull, clear, and exact description of the invention, such as will enahleothers skilledginthe art to `which 1t appertains to make 'and "use thesame.

The present invention relates to a current indicator or detector, andhas for its object the production of a device'which will be eX-ceedingly sensitive to smallehanges in the energy received, and one thatwill be easy to operate, and not liable to get-out of order.

To these ends the invention consists in the novel details andcombinations of parts more fully hereinafter disclosed and particularlypointed out in the claims. Y j

Referring to the accompanying' drawings forming a part of thisspecification in which like numerals also refer to'like parts in all theviews: Figure l, is a diagrammatic View showing' one form el' the`invention, in which only a single sensitive` conducting' element isemployed. Fie. is a like View showing a modification, in which a.plurality of such elements in series are employed; and. Fier. 3, is aView similar to Fig. 2 but showing' a plurality ol the sensitiveelements joined in parallel. V

It is well known that certain salts and mix tures ol salts which areonly slie'htlyjeonductive at certain their' condinttivities as thetemperature rises to a certain critical point, lwhich grenerally dillersfor each salt; and it is also well known that alter thc temperaturepasses the said critical point, these.. salts .have the remarkableproperty ol increasing' their eonductivities at a rate l'ar higher thanthe lrate at which said conductivities were increased. before said'point wa.; reached. ArnoneY such salts may be mentioned certain. oxideof the metals, for example, cupric oxid (IL10, magnesium oXid, andplumhie oxid. Also, certain halogen compounds, as for example the.mercury suhlimates, and certain oXids; as well as certain sulfide andeven ordinary glass. l take advantage ol these properties by providing asensitive coinlucting; element 1 consisting' of a suittive conducting'element, or

temperatures, increaseable quantity of such a salt or a mixture of suchsalts, and join it in a circuit 2, provided with a suitable rheostat 3,a source ol current 4, and any suitable telephone rc ccivcr, currentdetector, indicator or re* eerder 5. i

6 represents'anaerial adapted to receive l'lertzian waves; 7 a coilsurrounding: said element 1, joined to said aerial and grounded as at 8.l

In Fig'. 2,'a plurality of sensitive elements are employed joined inseries; and in Fie'. :l some of said elements are joined in parallel. Inoperation sullicient current may he lirst passed through the coil 7`surrn11nlinu the sensitive element 1 to raise it to or aliove the criticaltemperature 5 or it may he raised to sueh critical temjicrature and keptthere by any other suitable means, and the current then passingrtl'n'oue'h may be suitahly regu-f lated toiaid in koe/piney the saidsensitive elcment at or aliove its critical point. In-

either caseI any increase of temperature heyond the critical point willvery greatly reduce the electrical resistance ol said clement orelements 1, and'therelore the indicatingil or other instrument 5 willTshow such lact. Therefore, if electro-magnetic waves, diag'rammaticallyindicated at l), impinge upon the aerial (l, a current will traverse thecoil 7 and increase the temperature of the` sensielcments l, which willat once permit a larger current to .flow t u'ough the circuit 2, and theinstrument 5 will disclose` that fact.` In this way very minutechanecsip thc'reeeivcd eiierey may be detected .andn 'ad as tclcgraphico1' othersignals, oi" as 'ai late speech.

lt is apparent that th device is capable ol general application when.used lfothc detection ol very small. changes in the energy rew ceivedv,and therefore l do no! wish to. lie limited to any single specilic use.A

lhat l4 claim is z.` i

l. .ln the art ol detecting' weak currents, a

sensitive conductine element comprising in' its composition a chemicalsalt havin;r the property ol changing its conductivity as itstemperature changes until a critical temperature is reachedfand thenincreasing. said conductivity at a' dillerent rate for further changesof temperature, substantially as described. f

. A member of a` detector for weak currents which comprises in itscomposition a metallic oxid, whose conductivity is sensitive to changesin temperature, and which is conductively oined to both terminals of thedetector circuit, substantially as described.

3. A detector for weak currents provided with an indicator, and asensitive conducting element comprisingr a metallic oXid conductivelyjoined to both terminals of the indicator circuit, Whose conductivitychanges as the tcniperature changes, and a heater for said element,substantially as described.

4. ln a Hertzien wave detector the combination of a sensitive salt Whoseconductivity changes with changes in the temperature; a com pletemetallic circuit passing through the same; means to detect weak currentsin said circuit; and means for heating said element, substantially asdescribed.

5. Means for detecting Hertzian waves, comprising` a sensitiveconducting` element composed of a metallic oXid; a circuit including vadetector for weak currents passing1 through said element; an aerial; anda coil surrounding said element joined to said aerial, substantially asdescribed.

G. Means for detecting Hertzian Waves, comprisingr a plurality ofsensitive conductingeleinents composed oi metallic oxids; a

circuit. in which said elements are included; means for heating saidelements; a detecting instrument; and an aerial j eined to said .heatingmeans, substantially as described.

7. ln a Hertzian wave receiver, the coinbination of a plurality ofsensitive conducting` elements composed of cupric oXid; a circuitpassing1 `through said elements; a current detector in said circuit; aplurality of coils surrounding said elements; and an aerial to whichsaid coils are connected, substantially as dcscri bed.

ln'testimony whereof7 l a'fliX my signature, in presence ol twowitnesses.

CLIFFORD l). BABCOCK.

YVitnesscs-z I CHARLES FULLER, WiLLmM J. CANARY.

